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3: Paeds Y3/4 - Paediatrics [15] > [42] Down's Syndrome > Flashcards

[42] Down's Syndrome Flashcards

1
Q

What is Down’s Syndrome also known as?

A

Trisomy 21

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2
Q

What is meant by Trisomy 21

A

The patient has three copies of chromosome 21

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3
Q

Is the extra copy of 21 a full or partial copy?

A

Can be either

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4
Q

How common is Down’s Syndrome compared to other autosomal trisomies?

A

It is the most common

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5
Q

How common is Down’s Syndrome in terms of causes of severe learning difficulties?

A

It is the most common

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6
Q

What can the extra chromosome 21 occur as a result of?

A

Non-disjunction, translocation or mosaicism

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7
Q

What is the most common cause the extra chromosome 21?

A

Meiotic nondisjunction

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8
Q

How many cases of Trisomy 21 are due to meiotic nondisjunction?

A

94%

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9
Q

What happens in meiotic nondisjunction?

A

Chromosome 21 fails to separate leaving one gamete with 2 and on game with none

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10
Q

In order for Down’s Syndrome to occur in meiotic non-disjunction, which gamete must be fertilised?

A

The one with two chromosome 21 copies

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11
Q

What increases the likelihood of meiotic non-disjunction in the maternal gamete?

A

Increasing maternal age?

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12
Q

Can meiotic non disjunction occur in spermatogenesis?

A

Yes

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13
Q

What does meiotic non-disjunction during spermatogenesis mean?

A

That the abnormal gamete can be of paternal origin

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14
Q

What percentage of Down’s Syndrome cases are caused by translocation?

A

5%

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15
Q

What is a Robertson translocation?

A

When the extra chromosome 21 is joined onto another chromosome

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16
Q

Do all people with Robertson translocation present with symptoms?

A

No, some are phenotypically normal carriers

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17
Q

What test is recommended due to the ability for phenotypically normal carriers to exist?

A

Parental chromosomal analysis

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18
Q

What percentage of Down’s Syndrome is caused by mosaicism?

A

1%

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19
Q

What is mosaicism?

A

Where some cells are normal and some have trisomy 21

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20
Q

How does mosaicism usually arise?

A

Zygote is chromosomally normal but non-disjunction occurs during mitosis

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21
Q

What is sometimes the case in patient with mosaicism forms of trisomy 21?

A

The phenotype is milder

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22
Q

What is the main risk factor for development of Down’s syndrome?

A

Older mother

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23
Q

What are the main signs of Down’s Syndrome?

A
  • Characteristic craniofacial appearance
  • Short neck
  • Single palmar crease
  • Incurved and short 5th finger
  • ‘Sandal gap’ between 1st and 2nd toes
  • Hypotonia
24
Q

What are the characteristic craniofacial features of Down’s Syndrome?

A
  • Round face
  • Flat nasal bridge
  • Upslanted palpebral fissures
  • Epicanthic folds
  • Brushfield spots in iris
  • Small mouth and protruding tongue
  • Small ears
  • Flat occiput and third fontanelle
25
Q

How is Down’s Syndrome often picked up?

A

Antenatal screening

26
Q

What are all pregnant women offered with regards to antenatal screening for Down’s Syndrome?

A
  • Blood biochemical marker tests

- USS to look for nuchal thickening

27
Q

What are women with an identified increased risk offered?

A

Amniocentesis

28
Q

What does amniocentesis allow?

A

Checking of fetal karyotype

29
Q

What are becoming increasingly available to allow early detection of Down’s Syndrome in pregnancy?

A

Non-invasive karyotyping techniques

30
Q

What should happen if there is clinical suspicion of Down’s Syndrome following birth?

A

A senior paediatrician should discuss this with the parents

31
Q

How should a post-birth diagnosis of Down’s Syndrome be confirmed?

A

Chromosome analysis

32
Q

What technique can be used to analyse chromosomes after birth?

A

Interphase FISH

33
Q

What is another trisomy that should be considered when diagnosing Down’s Syndrome?

A

Trisomy 18

34
Q

What is trisomy 18 also known as?

A

Edward’s Syndrome

35
Q

What other conditions should be considered as differentials for Down’s Syndrome?

A
  • Multiple X Syndrome

- Zellweger syndrome

36
Q

What further testing should children with Down’s Snydrome be referred for following birth?

A
  • Detailed cardiac assessment
  • Hip ultrasound
  • Audiology
37
Q

What is the role of a clinical geneticist in the management of Down’s Syndrome?

A

Genetic counselling

38
Q

What may be useful to help parents cope with their child being diagnosed with Down’s Syndrome?

A

Access to support organisations e.g. Down Association

39
Q

In the long-term how are patients with Down Syndrome continued to be managed?

A
  • Follow-up by MDT
  • Physiotherapy
  • Annual TFT
  • Audiology and ophthalmic assessment every 1-2 years
40
Q

What is the main cause of early death in Down’s Syndrome?

A

Congenital cardiac diseases

41
Q

Excluding congenital cardiac diseases, what is the life expectancy of a person with Down’s Syndrome?

A

Well into adult life

42
Q

What do most patient’s with Down Syndrome develop by their 40’s?

A

Alzheimer’s

43
Q

What is the effect of most patient’s with Down Syndrome developing Alzheimer’s by their 40’s?

A

Life expectancy is somewhat shortened from average

44
Q

How do the majority of patient’s with Down Syndrome live in adult life?

A

Semi-independently with supervision

45
Q

What congenital diseases are associated with Down’s Syndrome?

A
  • Congenital heart defects
  • Duodenal atresia
  • Hirschsprung’s
46
Q

What percentage of patient’s with Down’s Syndrome have congenital heart defects?

A

40%

47
Q

What percentage of patient’s with Down’s Syndrome have Hirschsprung’s?

A

~1%

48
Q

What later medical problems may a person with Down’s Syndrome be at increased risk of developing?

A
  • Delayed motor milestones
  • Learning difficulties
  • Short stature
  • Increased susceptibility to infections
  • Otitis media w/ effusion
  • Visual problems
  • Increased risk of leukaemia and solid tumours
  • Acquired hip dislocation
  • Atlantoaxial instability
  • Obstructive sleep apnoea
  • Hypothyroidism
  • Coeliac disease
  • Epilepsy
  • Early onset Alzheimer’s
49
Q

What percentage of patient’s with Down’s Syndrome develop otitis media with effusion?

A

75%

50
Q

What is the consequence of otitis media with effusion?

A

Hearing impairment

51
Q

What effect may hearing impairment have on development?

A

Slow, especially speech

52
Q

What visual impairments may develop in Down’s Syndrome?

A
  • Cataracts
  • Squints
  • Myopia
53
Q

What percentage of patient’s with Down’s Syndrome develop cataracts?

A

15%

54
Q

What percentage of patient’s with Down’s Syndrome develop myopia?

A

50%

55
Q

What percentage of patient’s with Down’s Syndrome develop obstructive sleep apnoea?

A

50-75%

56
Q

What percentage of patient’s with Down’s Syndrome develop hypothyroidism?

A

15%

3: Paeds Y3/4 - Paediatrics [15] (115 decks)

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